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Thursday, February 7, 2008

Stress during Pregnancy associated with Schizophrenia of Children

A recent article in the Archives of General Psychiatry reports that women who undergo an extremely stressful event during the first three months of pregnancy have an increased risk of having children who develop schizophrenia.

Researcher Ali S. Khashan of the University of Machester, England and colleagues note that there is some consensus that a mother's psychological state influences her unborn baby. "Severe life events during pregnancy are consistently associated with an elevated risk of low birth weight and prematurity." Schizophrenia is a disabling condition associated with abnormal brain structure and function, and it is believed to begin in early brain development. Risk of the condition is influenced by susceptibility genes that can interact with environmental factors that occur during pregnancy.

The data are drawn from 1.38 million Danish births occurring between 1973 and 1995. A national registry linked mothers to close family members, and the registry informed researchers if mothers experienced stressful events during pregnancy such as a family member dying or receiving diagnosis of cancer, heart attack, or stroke. The data allowed the research team to follow children from their 10th birthday through June 30, 2005 or until they died, left the country, or received a schizophrenia diagnosis. During the study period, 21,987 mothers were exposed to the death of a relative during pregnancy, 14,206 were exposed to serious illness of a relative during pregnancy, and 7,331 of the offspring developed schizophrenia.

One result suggests a 67 percent greater risk of schizophrenia or related disorders among the children of women who experienced the death of a relative during the first trimester of pregnancy. The researchers note that if the death of a relative occurred up to six months before conception or any other time during pregnancy, the event was not associated with a risk for schizophrenia. In addition, a mother's exposure to a relative's serious illness is also not linked to schizophrenia.

Only for individuals without a family history (parents, grandparents or siblings) of mental illness was there a significant association between a family death and risk of schizophrenia.

The authors conclude that "risk associated with exposure to a well-defined, objective stressful event confined to the first trimester of pregnancy suggests a number of possible mechanisms." They suggest a possible effect on the fetus' brain of chemicals released by the mother's brain when she experiences stress. During early pregnancy, the protective barriers between the mother and fetus are not fully constructed, and the effects may be strongest.